1. Field of the Invention
The present invention relates to a mechanism including an inverted planetary optical system for photographically recording documents, data, and the like on microfilm, and relates more particularly to an improved method and device for advancing and processing the exposed microfilm.
2. Description of the Prior Art
Microfilm developing apparatus of the above type, conventionally, employ an optical system including an objective lens for producing an image or recording of an object on a given frame of the film. Typically, this is accomplished by initially illuminating the object and subsequently directing the resulting optical beam on to the frame of the film to produce an image thereof.
Following exposure of the film, the next step is to properly advance the film for the next cycle of operation. It has, heretofore, been conventional to first expose the film and then to advance the film so that the film is lodged in the proper position for the next succeeding exposure. Known in the art are films with edge-wise film positioning perforations and films having no perforations but which are guided by pinch rollers. Those films having positioning perforations are arranged such that the position of the film is determined by the given position of the perforations. When the film is first inserted into the system, the perforations may not be perfectly aligned with the film advancing mechanism so that the first film advance operation may result in a film movement which is less than a full picture frame to be exposed. This is a serious problem when reliance is to be placed upon accurate recording of documents.
In prior art microfilm recording systems, it has been common practice in the development of exposed film to provide a plurality of tanks each containing a different film processing liquid such as a developing liquid, a fixing liquid and a washing liquid. In each tank there usually are provided rollers at the top and bottom thereof and immersed in the film processing liquids. Other rollers have been provided between the tanks. The film or film strip to be processed is guided over these rollers in a generally annular path to form one or more loops in each tank. It has been common practice in the past to drive each of the rollers at the same speed to advance the film evenly through the tanks.
Such an arrangement has the disadvantage that the rotating rollers tend to stretch and mar the surface of the wet film strip, considering that the roller surfaces are in direct physical contact with the major surfaces of the film. A further disadvantage with this type of arrangement is that if there is any speed differential between the rotating rollers, the roller contact with the film surfaces produce not only image distortion but also film breakage due to excess tensioning of the film strip between and against such contacting services.
Still another disadvantage of such prior art apparatus is that the rollers solely determine the path that the film is to take. This becomes extremely objectionable where a thin base film is being employed, and the axis of one or more of the rollers is slightly off-line. The result of such misalignment will be that a thin base film will tend to track to one edge of each misalinged roller where it will bunch up. Additionally, the prior art processing systems require temperature limitations as regards the processing liquids.